The disclosure is based on a fastening assembly for a sensor assembly of the generic type of independent patent claim 1, and on a corresponding sensor assembly of the generic type.
Active and passive safety systems such as, for example, restraint systems such as, for example, airbags, seat belt pretensioners etc. as well as systems for controlling the vehicle movement dynamics such as, for example, ESP, ABS etc. are used in modern motor vehicles. An essential component of such systems are inertial sensors which are used to measure accelerations and/or yaw rates and/or rotation rates of the motor vehicle and are preferably embodied as micro-mechanical or micro-electromechanical sensors. During operation, such sensors are made to move in an oscillating fashion by suitable mechanical excitation, and forces and/or accelerations which occur are measured and evaluated.
German laid-open patent application DE 10 2007 058 965 A1 describes, for example, a motor vehicle sensor housing for a motor vehicle sensor having an insertion part. The described motor vehicle sensor housing is manufactured from polypropylene in a region of the insertion part in order to damp a sensor module which is arranged in/on the motor vehicle sensor housing. The motor vehicle sensor is preferably embodied as a micro-mechanical or micro-electromechanical sensor such as, for example, an inertial sensor which is preferably constructed as a rotation rate sensor or airbag-triggering sensor. The sensor module can be embodied in one piece with the sensor housing, or the two components can be permanently connected to one another by a mechanical connection. The insertion parts can be embodied, for example, as at least one metallic supporting bush which serves to support fastening forces acting on the sensor housing, which sensor housing is fastened to a fastening means on the bodywork.
A problem which frequently occurs when inertial sensors in motor vehicles are used is that of interference accelerations which can occur depending on the installation location of the sensor. These interference accelerations have a particularly large influence on the output signals of the sensor if they have frequencies in the region of an excitation frequency of the sensor or a natural frequency of the sensor assembly. On the basis of oscillation measurements and FEM analyses (FEM: Finite Element Method) it is possible to demonstrate that overshoot factors, which arise owing to eigenmodes of the housing, can interfere massively with signals of the inertial sensors. A particularly destructive influence is caused by the first eigenmodes in the frequency range from 30 Hz to 4 kHz. Within this frequency range, a relatively high degree of sensitivity of the inertial sensors, in particular of a two-axle acceleration element, can be detected.